Le Duc Cuong, Do Huy Toan, Dao Dinh Cham, Nguyen Ba Thuy, Nguyen Ba Thuy, Du Van Toan, Nguyen Minh Huan, Nguyen Quoc Trinh, Tran Anh Tu, Le Xuan Sinh

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In the present study, an open-source coupled numerical model based on Delft3D source code was performed and applied to simulate the hydrodynamic changes due to the Super Typhoon Rammasun in the Gulf of Tonkin (GTK). The results indicated that the typhoon strongly affects the current, water level, wave fields, and suspended sediment transport in the western coastal areas of the GTK. The simulated wave height field reflects the wavefield caused by the Super Typhoon Rammasun, and the maximum wave height was 6.8m during the Typhoon Rammasun event. The current is affected by the strong wind caused due to the typhoon in the surface layer. Accordingly, current velocity and significant wave height increased distinctly by 4 and 9 times, respectively, more than the normal condition. In the western coastal areas, the maximum sea level falls to about 0.7m, and the current velocity was 0.25-0.3m/s (during ebb tide stages) greater than it was in normal conditions during Super Typhoon Rammasun event. The moving Super Typhoon Rammasun resulted in suspended sediment concentration (SSC) increasing by 2 times more than normal monsoon conditions and also strengthened suspended sediment transport in the GTK, which was mostly controlled by strong waves during typhoon events. Simulated results showed that SSC in the GTK varied dramatically in temporal and spatial distribution, with the maximum value in wet seasons because of large sediment discharge around the river mouth.


Keywords: Gulf of Tonkin, Delf3D, Rammasun Typhoon, Hydrodynamics, Suspended Sediment


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